The conventional side mirrors installed in the right and left sides of automobiles for the safety driving assistance are equipped with electric power system that enables to adjust the mirror angle carried out by means of a remote control system for the purpose of controlling by the drivers sitting in the automobile cabins (referring to the reference 1 as an example) to obtain good view angles.
Reference 1
Published Utility Model Application: JP, 05-27304, Y (1993)
The adjustment device of electric power mirror (abbreviated as an “adjustment device”, hereinafter) has conventionally a mechanism shown in the FIG. 7A as a mirror holder 100 to hold a mirror (which is not drawn in the figures) can be tilted around the center of a semi-globe to which inner surface of a salient 101 formed in the holder 100 smoothly contacts and two adjustment nuts 200 (only one adjustment nut is drawn in the figures)of the mechanisms enable the mirror angle to be adjusted in the vertical plane and the horizontal plane against the front or the back direction of the automobile. More concretely, this mirror holder 100 can be tilted by means of the adjustment nuts 200 (one of the adjustment nuts is shown in FIG. 7A) installed in two positions in the mirror holder 100 so that the adjustment nuts can adjust the orientation of the mirror against the direction of the driving direction of the automobiles.
The adjustment nut has a globe-like pivot 200 formed in an end thereof and the globe pivot fits to a recess 102 which has inner-globe shape to hold the pivot 201. The other end of the adjustment nut 200 is formed into a plural of legs 202 which are elastically deformable and of which tips have nail portions 202a fitting onto the surface of the screw portion 301 of an external thread made in the actuator housing 300. Ribs 203 formed on the outer surface of the adjustment nut 200 is fitted into a trench 401 made in a worm wheel 400 and can slide therein along the trench but cannot rotate without obstruction against the worm wheel, in other wards the adjustment nut cannot relatively rotate against the rotation of worm wheel. Therefore the adjustment nut 200 can move as screw-in or screw-out in the direction of the rotation axis of the worm wheel 400 in accordance with the rotation of the worm wheel.
In this conventional construction of the adjustment device, the combining force between the nail portion 202a and the screw potion 301 is created by the elastic deformation of the legs 202 formed at an end of adjustment nut 200. However the combining force between the pivot 200 and the recess 102 that holds the pivot is stronger than the above combining force between the nail portion 202a and the screw potion 301. Therefore, when the mirror is dismounted from the mirror holder 100 in the service of mirror exchange, the adjustment nut 200 which is pulled by the mirror holder 100 tends to be put out of the screw-in position with the screw portion 301 once the mirror holder 100 is strongly pulled down in conjunction with pulling of the mirror attached to the mirror holder.
Once the adjustment nut 200 is pulled off from the screw potion 301 made in the actuator housing 300, it is necessary to disassemble the actuator housing 300 in order to put the adjustment nuts back in the screw-in position with the screw portion. Therefore, it is the problem such that the mirror exchange service needs a time-consuming work more than a simple part exchange process.
It may be possible to push the adjustment nut 200 into the screw-in position of the screw portion 301 of the actuator housing 300 by means of strong insertion force. However, the nail portion 202a may be broken due to such strong insertion force. For this insertion of the adjustment nut, it is necessary to position the rib 203 to be aligned and fitted into the trench 401 made in the worm wheel 400. This is a difficult hand work. Therefore the work needs high skill in such assembly. In addition, a rubber boot (not shown in FIG. 7A or FIG. B) that covers the surrounding portion of the adjustment nut 200 can block the sight to check the correct positioning of the rib 203 fitted into the trench 401. Therefore the reassemble work itself is difficult.
The purpose of the present invention is to offer an adjustment device that has a preventive mechanism by which the nail portion 202a in the adjustment device cannot be pulled off from the screw portion of the actuator housing even when the mirror holder is strongly pulled down in the service of the mirror exchanging.